Patent attributes
In an internal combustion engine variable compression ratio system, a compression ratio of an internal combustion engine is changed over between a high compression ratio and a low compression ratio with a changeover threshold value corresponding to a predetermined operational condition of the internal combustion engine being a boundary. When the internal combustion engine enters a slow acceleration state or a slow deceleration state, a changeover is performed first and then the state is maintained for a predetermined period by prohibiting re-changeover. Therefore, changeover hunting can be prevented in the system while maintaining an appropriate compression ratio in conformity with traveling characteristics demanded by a driver, when the internal combustion engine in a state of slow acceleration or slow deceleration.
